When an analysis is performed by using a gas chromatograph, a carrier gas is supplied to a sample vaporization chamber, and a sample vaporized in the sample vaporization chamber is introduced into a column together with the carrier gas. The column is heated to a high temperature, and a sample component separated while the sample passes through the column is detected in a detector. In order to prevent a damage to the column, a carrier gas is continuously supplied into the column even after the analysis is finished; however, upon exchange of the column or the like, the temperature of the column is sufficiently lowered, and then supply of a carrier gas is stopped (see Patent Document 1 listed below).
An analysis will not be performed for a long time after the power supply of the gas chromatograph has been switched over from an ON state to an OFF state. Therefore, if a carrier gas is continuously supplied after switchover of the power supply, the carrier gas is wastefully consumed. Therefore, an operator conventionally performs work of manually setting parameters in order to lower the temperature of the column and to reduce the flow rate of the carrier gas.